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The majority of head and neck cancers are related to alcohol and tobacco use (75%). However, human papillomavirus (HPV) has been shown to be related to between 15-25% of head and neck cancers worldwide. In certain head and neck cancers, such as those involving the oropharynx, tonsil, and tongue, HPV has been associated with 50-90% of the squamous cell carcinomas (SCC) which arise from these regions.

Studies have suggested that the rate of head and neck cancers is rising in patients without a history of alcohol or tobacco use. Other studies have shown that there is an increased incidence of tonsillar cancer is the husbands of women with cervical cancer.

HPV 16 and 18 are considered high risk HPV's and are associated with cervical cancer and certain subsets of head and neck squamous cell carcinomas (HNSCC).

The development and implementation of the HPV vaccine for HPV 16 and 18 was the basis for this study to assess the incidence of squamous cell carcinoma of the tonsil, oropharynx and tongue.

Materials and Methods

The present study examined patients from the Surveillance, Epidemiology and End Results (SEER) database and the CDC's National Program of Cancer Registries datatbase. The data was collected from 1998 to 2003 and encompassed 83% of the U.S. population. Only data from patients with SCC of the base of tongue (BOT), oropharynx, and tonsil was collected.

Additional data collected included the age, gender, race/ethnicity, stage, US region, and year of diagnosis for the patient.

Incidence rates were age-adjusted to the 2000 U.S. standard population and expressed per 100,000 individuals.

Results

From 1998-2003 the annual incidence rates per 100,00 people was 1.16 (95% confidence interval (CI) 1.14-1.18) for BOT, 0.90 (95% CI of 0.89-0.92) for oropharyngeal and 1.35 (95% CI 1.34-1.37) for tonsillar SCC.

Tonsillar cancer incidence was highest in Caucasians (1.37), followed by Hispanics (0.89), American Indians/Alaska Natives (0.85), and Asian/Pacific Islanders (0.49).

The Southern region had the highest incidence of tongue (1.24), oropharyngeal (1.06), and tonsillar SCC (1.52). These findings are consistent with data from cervical cancer incidence studies.

There was a significant annual increase in BOT (2.68%) and tonsillar cancers (2.96%) from 1998-2003.

The peak incidence of HPV related HNSCC tended to occur between 40-70 years of age with a peak towards the younger side of this distribution. HPV related HNSCC tended to be predominantly in males.

Author's Conclusions

The Authors' note that the limitations of this study included:

The use of retrospective data and the analysis of only HPV related HNSCC.

The Southern region was not well represented in the data.

There was no data available for history of tobacco or alcohol use.

There were no tissue samples and hence no way to examine HPV status of the patients in this study.

Strong aspects of this study:

This study examined a large population of patients encompassing the majority of the U.S. By combining the two databases a more accurate measure of incidence may be obtained.

This study provides a baseline prior to the wide spread use of the HPV vaccine.

Based on the results of this study the authors' suggest that the HPV vaccines may have a significant impact on HNSCC. They also found that HPV related HNSCC tended to occur in younger African American males.

Clinical/Scientific Implications

This study provides an important baseline incidence for the period directly prior to the use of the HPV vaccine (1998 to 2003). This provides a reference point from which to determine the effects that the HPV vaccine may have on the incidence of HNSCC. It confirms many of the findings from similar studies which have examined HPV's incidence in the U.S. (ASCO abstract 6000). However, there are some disparities, such as the racial distribution between the two analyses which need further study to confirm. The annual increase between 1998 and 2003 suggests that the rate of HPV related cancers is increasing greatly, though smoking is decreasing in young males. This suggests that HPV infection may be contributing to this increase, perhaps due to changes in sexual behavior among younger males leading to more frequent infection.

The present study suggests that the HPV vaccine may be effective in reducing the incidence of HNSCC. However, clearly further studies are necessary. The effectiveness of vaccinating men remains to be determined. Furthermore, how the vaccine will affect the distribution of the various types of HPV also poses an interesting question for future studies.

Apr 23, 2014 - Most oropharyngeal cancers in the United States diagnosed between 1995 and 2005 were positive for human papillomavirus (HPV), specifically HPV 16 or 18, according to a study published in the May issue of the U.S. Centers for Disease Control and Prevention's Emerging Infectious Diseases.